I’ve been running gld for more than two months now and it is truly efficient. The current statistics say:

# of entries in the database : 16077
# of one hit entries in the database : 15100
Oldest entry in database : 65 days ago

This means that almost 94% of the attempts to send mail through my server are only made once!

Unfortunately Facebook and Google Mail do not play well with greylisting, as attempts that are told Service temporarily unavailable, please try later by greylisting are very likely to be retried from a different IP. I’ve made a little script that scans /var/log/mail.log for such mail servers and add them to the gld whitelist table.

As a follow-up to my post about MySQL support for UTF-8 in PHP, here is the very same information for Ruby on Rails. In Rails it is a simple configuration entry in config/database.yml. I use the development configuration as an example: